JP 2005-348193 A (PTL 1) discloses an electronic device, such as a mobile phone or the like, that transmits air-conducted sound and bone-conducted sound to a user. As the air-conducted sound, PTL 1 discloses a sound that is transmitted to the user's auditory nerve by air vibrations, caused by a vibrating object, that are transmitted through the external ear canal to the eardrum and cause the eardrum to vibrate. As vibration sound, PTL 1 discloses a sound that is transmitted to the user's auditory nerve through a portion of the user's body (such as the cartilage of the outer ear) that is contacting a vibrating object.
In the telephone disclosed in PTL 1, a rectangular vibrating body, formed from a piezoelectric element (bimorph) and a flexible substance, is attached to an outer surface of a housing via an elastic member. PTL 1 also discloses that the vibrating body functions as a vibration unit as follows. When voltage is applied to the piezoelectric element in the vibration unit, the piezoelectric material expands and contracts in the longitudinal direction, causing the vibrating body to undergo bending vibration. Air-conducted sound and vibration sound are transmitted to the user when the user contacts the vibrating body to the auricle.